Which of the following is NOT a type of vision?

The correct answer is D, as "Chromatic" does not refer to a type of vision in the same context as the others.

Photopic vision refers to the type of vision that occurs under well-lit conditions, primarily involving the use of cone cells in the retina which are responsible for color perception and detail. This vision allows us to see clearly in bright light, such as during the day.

Mesopic vision describes the vision that occurs in intermediate lighting conditions, such as during twilight or dawn. This type of vision involves both cone and rod cells, allowing us to see in varying light levels while still distinguishing some colors.

Scotopic vision deals with low-light conditions, where rod cells become the predominant photoreceptor. This type of vision occurs in dim lighting and is primarily responsible for seeing in dark environments where color perception is limited, and we rely more on sensitivity to light.

In contrast, "Chromatic" refers to qualities of color but is not classified as a type of vision. Therefore, it stands apart from the other three terms, which specifically describe how humans see in different lighting situations.